The handler.get()
method is a trap for getting a property value.
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Syntax
const p = new Proxy(target, { get: function(target, property, receiver) { } });
Parameters
The following parameters are passed to the get()
method. this
is bound to the handler.
target
- The target object.
property
- The name or
Symbol
of the property to get. receiver
- Either the proxy or an object that inherits from the proxy.
Return value
The get()
method can return any value.
Description
The handler.get()
method is a trap for getting a property value.
Interceptions
This trap can intercept these operations:
- Property access:
proxy[foo]
andproxy.bar
- Inherited property access:
Object.create(proxy)[foo]
Reflect.get()
Invariants
If the following invariants are violated, the proxy will throw a TypeError
:
- The value reported for a property must be the same as the value of the corresponding target object property if the target object property is a non-writable, non-configurable own data property.
- The value reported for a property must be undefined if the corresponding target object property is a non-configurable own accessor property that has
undefined
as its[[Get]]
attribute.
Examples
Trap for getting a property value
The following code traps getting a property value.
const p = new Proxy({}, { get: function(target, property, receiver) { console.log('called: ' + property); return 10; } }); console.log(p.a); // "called: a" // 10
The following code violates an invariant.
const obj = {}; Object.defineProperty(obj, 'a', { configurable: false, enumerable: false, value: 10, writable: false }); const p = new Proxy(obj, { get: function(target, property) { return 20; } }); p.a; // TypeError is thrown
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of '[[Get]]' in that specification. |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
get | Chrome Full support 49 | Edge Full support 12 | Firefox Full support 18 | IE No support No | Opera Full support 36 | Safari Full support 10 | WebView Android Full support 49 | Chrome Android Full support 49 | Firefox Android Full support 18 | Opera Android Full support 36 | Safari iOS Full support 10 | Samsung Internet Android Full support 5.0 | nodejs Full support 6.0.0 |
Legend
- Full support
- Full support
- No support
- No support